This invention relates to improved methods and apparatus for using a plurality of light sources to illuminate an area or aperture. The invention discloses improvements to devices using a plurality of light sources where the plurality of light sources are multiple wavelengths and may be light emitting diodes (also called in this application xe2x80x9cLEDsxe2x80x9d). The inventions contained within the text are directed at hand held flashlights, theatrical lighting, and may have other applications. Theatrical lighting is used in concerts, special events, nightclubs, television studios, restaurants and theme parks.
When using a lighting device to illuminate an area it is often found necessary to change the profile of the projected light to match the object to be illuminated. When using a conventional hand held flashlight for example often the flashlight is equipped with a means for changing the profile of the emitted light from a spot to a wash. When using a conventional reflector and a single light source the reflector is often moved in relative position to the source to accomplish changing the profile. U.S. Pat. No. 4,987,523 to Lindabury discloses an illumination device that moves the lamp in relative position to the reflector.
U.S. Pat. No. 4,855,884 to Richardson discloses a variable beamwidth stage light with a single light source, relying on an axially movable reflector for changes in beamwidth. The reflector is constructed of a plurality of reflective leaves that are moved by a motor to change the focal length of the reflector. When working with a plurality of light sources, various methods have been disclosed that enable the multiple light sources to be converged or diverged. U.S. Pat. No. 4,729,070 to Chiu discloses an adjustable ring for concentrating multiple beams of light. Chiu discloses an apparatus for changing the angle of incidence of a plurality of light sources arranged in a ring. A threaded holder surrounds the ring of light sources while a cam mechanism adjusts the angle of the light sources that is operated by turning the threaded holder. U.S. Pat. No. 5,752,766 to Bailey et al. discloses a multi-color focusable LED stage light. A linear actuator is operable to move a base member containing an array of LEDs which in turn cause the LED array to change the direction of the optical axes of a substantial number of LEDs. By deforming the base member 20 in Bailey, the LEDs can be converged or diverged on an area to be illuminated.
The Bailey patent does not discuss the issues of thermal management. High intensity light emitting diodes (LEDs) have a critical upper temperature operating limit. This can easily be exceeded when the LEDs are arranged in-groups as in the Bailey patent and the ambient air temperature rises.
Multiparameter lights of the prior art utilize a single light source with motors to vary the focus, color, position and intensity. U.S. Pat. No. 3,845,351 to Ballmoos et al. titled: METHOD AND APPARATUS FOR THE ADJUSTMENT OF A PLURALITY OF FLOODLIGHTS discloses a number of floodlights especially for the illumination of a stage or studio, in which the parameters azimuth, elevation, brightness, focus and color of a bundle of light rays of each floodlight are adjusted to an optimum value for any one of a plurality of lighting effects.
U.S. Pat. No. 4,392,187 to Bornhorst titled: Computer controlled lighting system having automatically variable position, color, intensity and beam divergence illustrates another example of the prior art. Each of the instruments houses a central lamp and an optical system designed to collimate the light from the lamp and vary the parameters of the light by inserting motor driven optical components into the light by remote control.
Multiparameter lights are generally controlled by a central control system via a serial data communications system. An operator operating the central control system may control each multiparameter light separately to adjust the parameters. Each multiparameter light may be provided with a communications address so that each multiparameter light may be addressed separately by an operator operating the control system
Multiparameter lights of the prior art are depicted in the High End Systems Product Line 1997 brochure.
The present invention in one embodiment provides an inexpensive method of converging and diverging a plurality of light sources by mounting the light sources to a flexible substrate that may be deformed to change the angular relationship of the plurality of light sources. Mechanical systems for deforming the base member or substrate are disclosed.
In the preferred embodiment of the invention, the flexible substrate is laminated with a conductive material to supply electrical current to a plurality of light emitting diodes. The light emitting diodes are arranged symmetrically around the substrate to provide uniform illumination. A battery cell supplying electrical current is engaged with the flexible substrate as to provide electrical contact and to provide a variable force on the substrate. The variable force on the flexible substrate flexes the substrate and in turn changes the direction of the concentration or rays of light from the light sources, (which may be light emitting diodes), changing the angle of incidence of the light emitted by the light sources. A threaded member may be used to adjust the force on the flexible substrate applied by the battery cell.
In another embodiment of the present invention an electromagnetic force is applied to the flexible substrate and used to deform the substrate. In yet another embodiment of the invention a motor and lead screw is used to selectively deform the substrate. In another embodiment, a cam is used.
In another embodiment of the present invention a light is constructed with multiple light sources that include multiple wavelengths. The light sources"" intensity or enabling may be individually controlled by wavelength groups or each individual LED may be controlled. Furthermore subgroups of the same wavelength or subgroups of multiple wavelengths may be individually enabled or there intensity controlled. The plurality of light sources may consist of light sources that emit wavelengths for red, green and blue light. The light utilizing the multiple light sources may use the red, green and blue wavelengths in a system of additive color mixing. U.S. Pat. No. 5,752,766 to Bailey et al., is incorporated by reference herein and specifies a system of additive color mixing. The multiple light sources may also contain additional wavelength LEDs such as amber or yellow LEDs. Also broad-spectrum visible white light emitting diodes such as those manufactured by Nichia Chemical Corporation of Japan may be included. A broad spectrum white light source may be added to the plurality of light sources to aid in the overall output of white light or to be mixed into variations of the colored light sources to produce further variations of pastel colors that would not be achievable by using a conventional additive Red, Green and Blue color mixing system.
The term xe2x80x9cwhite light LEDxe2x80x9d refers to a light emitting diode that provides a spectrum that is seen by the human eye for all purposes as white.
In yet another embodiment a substrate is mounted with a plurality of light sources. One of the important design restraints found while designing lighting instruments is the removal of heat generated by the light source. High intensity light emitting diodes (LEDs) have a critical upper temperature operating limit. This can easily be exceeded when the LEDs are arranged in-groups and the ambient air temperature rises. In one embodiment of the present invention this problem is solved by the use of ventilation holes placed through the flexible substrate. Ventilation holes are strategically placed in the substrate as to provide airflow either by a forced air system or by convection and to assist in dissipation of unwanted heat that is generated by the light sources and increase the life of the light sources.
In yet another embodiment a multiparameter light is disclosed that utilizes a plurality of remote controlled light sources in addition to remote controlled motors to vary the focus, color, position and intensity of the light emitted by the multiparameter light. Several multiparameter lights each utilizing a plurality of light sources may be remotely controlled by an operator or computer control system.
An improvement over U.S. Pat. No. 5,752,766 includes an additional colored LED such as yellow or amber. Artistic License a United Kingdom company has offered a lighting instrument called the xe2x80x9cColour-Fillxe2x80x9d that includes amber LEDs along with the Red, Green and Blue LEDs. This information can be found at xe2x80x9cwww.artisticlicence.com.xe2x80x9d
One improvement to the use of an additional colored LED such as amber or yellow is the use of a continuous spectrum white LED. Although the use of an amber or yellow LED along with the red, blue and green helps provide a wider range of color variation especially in the pastel ranges (or less saturated colors) it does not provide energy in the blue-green range. The addition of one or more white light LEDs help to provide a greater range of pastel colors including those in the blue-green wavelengths.
A light source constructed of a plurality of LEDs may also be constructed primarily of white continuous spectrum LEDs as shown in one embodiment of the present invention. White LEDs like that manufactured by Nichia are constructed of a phosphor that is radiated by short wavelengths similar to the standard fluorescent lamp. The advantage to a light source constructed of a plurality of white continuous spectrum LEDs is that the white light created by the LEDs contains energy throughout the visible spectrum. When creating white light through the use of an additive color system using red, green and blue wavelengths (RGB), the spectral energy adjacent to the red, green and blue wavelengths is usually omitted. An RBG system used to create white light can sometimes be problematic when illuminating objects that absorb or reflect very specific wavelengths of light. Illuminating these type of objects with RGB derived white light often may result in an erroneous perception of color by the viewer as compared to viewing the object under continuous spectrum white light.
The disadvantage to constructing a light source of white continuous spectrum LEDs is that color variations can not be provided. When providing a lighting instrument constructed of a plurality of white LEDs it can be of great advantage to adjust the color temperature of the emitted light. This advantage is similar to the manual selection of prior art fluorescent lamps that are xe2x80x9ccool whitexe2x80x9d or xe2x80x9csoft whitexe2x80x9d. By incorporating at least one additional wavelength light source such as an amber or yellow LED types, the perceived color of the light emitted by the white LEDs can be altered from a xe2x80x9ccoolxe2x80x9d or bluish white to a xe2x80x9csoftxe2x80x9d or yellowish light. The white continuous spectrum LED and an additional wavelength LED may either be individual LEDs separately packaged and fixed to a substrate or they may be manufactured so that both LEDs are contained within a single housing and the housing is fixed to the substrate. It is known in the prior art to package two narrow band (colored LEDs) in a single package for ease of handling and mounting.
Black light projectors are often used in entertainment along with fluorescent paints that radiate when exposed to specific frequencies of ultraviolet light. Black light projectors emitting ultraviolet light in the frequency range of 350 to 400 nanometers are often constructed of arc lamps in cooperation with an optical black light filter. Another common source of black light projection is the glass tube type black light that is constructed to mount in a standard commercially available fluorescent tube socket.
A unique type of black light projector used for entertainment can be constructed of solid state ultraviolet LED light sources. These ultraviolet light sources emit a very narrow band of ultraviolet light. One such LED is manufactured by Nichia Chemical Industries LTD of Japan. Part number NSHU590 emits ultraviolet light at 370 nanometers. Since the ultraviolet light emitted has a very narrow bandwidth, the emitted energy does not reach into the visible at 400 nanometers. It is best to have a visible wavelength emission indicator to indicate that the ultraviolet LEDs are emitting. An emission indicator can be constructed of one or more visibly emitting blue LEDs. The emission indicator would be mounted on the black light projecting instrument""s housing so as to be seen easily by an operator of the light. An example of a visible blue LED would be Nichia part number NSB500S. This blue LED wavelength centers itself around 465 nanometers. Any indicator of emission may be used including other colors of LEDs and other types of light sources. The blue LEDs may have a reduced output as to not attract great attention to the black light projector and risk a distraction during a performance, while still making it visible to theatrical lighting operators.
A black light projector constructed of ultraviolet LEDs has several advantages over the prior art devices. Conventional arc lamps used as the sources for black light projectors require high ignition voltages to xe2x80x9cstrikexe2x80x9d the lamp into operation. These lamps often emit a wide range of energy, incorporating unnecessary wavelengths that are filtered out by optical filters. The unwanted energy is often absorbed by the optical filter and turned into heat.
Since ultraviolet LEDs emit only an ultraviolet spectrum to begin with, less energy is wasted as compared to other prior art light sources that use an optical filtering system. Also LEDs do not require costly high voltage ignition systems such as required by prior art arc lamp systems. To provide additional effects in a theatre setting, the ultraviolet LEDs used to provide a black light effect can be strobed or flashed rapidly without great additional expense as the power supply to the LEDs does not have to incorporate a high voltage ignition system like that required in prior art black light projectors using arc lamps. A system of black light projection can be incorporated into a multi-parameter light that can be controlled remotely and may include other parameters like pan, tilt, strobe and dimming. A multi-parameter black light projector has the advantage of instant light output as the ignition system and warm up period like that required by conventional arc sources is not required. Also it can be easily positioned remotely by pan and tilt mechanisms so the projected light can be directed from one location to another. This is helpful as one light may do the job of several lights that do not have the parameters of pan and tilt. Since the black light projector of the invention does not require a warm-up period and emits light only at the desired ultraviolet frequency, energy is saved and the heat generated at the location of use is reduced.
While transporting or handling the devices, LEDs are much less susceptible to impact damage than arc lamp and filter projectors and much more robust than commercially available glass tube type black lights.
In yet another embodiment of the invention multiple light sources are built into a multi-parameter light having variable parameters. The light sources as a single group or color may have their intensity varied simultaneously. For example, in prior art lighting instruments using an RGB system with a plurality of light sources, the Red wavelength group of light sources would have their intensity varied simultaneously and at the same intensity level. The lighting instrument of the invention would be capable of individually varying the intensity of the light sources of the same wavelength or color in relation to each other. Each individual light source of the same wavelength may be varied in relation to each other or subgroups of the same wavelength may be varied in relation to each other. It is preferred that the light sources are fixed to a flexible substrate or that they are mounted on a curved substrate. In this way the light sources are not emitting light parallel to each other. As the plurality of light sources project light onto a projection surface and each of the light sources intensity is varied in relation to each other, the projected light will vary in intensity across the projection surface. Various methods of controlling the intensity of the individual light sources may be used. One method well known to vary the intensity of LED light sources involves current control of the device. This method could be applied to multiple light source LED lights using multiple wavelengths as described above. The light that is projected on a surface by the plurality of light sources that incorporates control over the individual light source intensities may have a graduated intensity across the projection surface depending on what multiple light sources has their intensity varied.
The present invention in various embodiments also provides for individual dimming of light sources.
The multiple LED light sources may also be flashed as to cause stroboscopic effects. The stroboscopic flash rates may be controlled from a theater remote control system. The stroboscopic flash rate of the multi-parameter light being controlled from a microprocessor that is an integral part of the lighting instrument. Other functions of a multiple light source multi-parameter light may include but are not limited to pan, tilt, dimming, strobe, focus, color adjustment and variable diffusion.
In yet another embodiment of the invention a variable light diffusing filter is included after the light sources. The variable light diffusing filter may be a variable filter such as a liquid crystal emulsion spread between sheets of conductive plastic. These filters are voltage controlled and in one state allows light to pass through a clear window. In another state (controlled by voltage) the light is scattered. When varying the controlling voltage to the liquid crystal filter it is possible to achieve variations in the amount of light being scattered. This is particularly useful as one parameter of a multi-parameter light, as the projected light can be varied in the softness of the edge of the projected light. A filter such as that described above is available form Edmond Scientific of Barrington N.J. and is manufactured by the 3M company.
The multiparameter lights of the invention disclose apparatus and methods for utilizing as the light source a plurality or light sources, in a multiparameter light while enabling the light generated by the plurality of light sources to be varied as to alter the focus, color, position and intensity of the projected light.